Pneumatically operated impact-action self-propelled mechanism

ABSTRACT

A pneumatically operated impaction mechanism for forming holes in the ground or the like in which a housing has a pointed working end and receives a reciprocable impact member to successively impose impact-force on the housing through a compressed air medium; and an air supply sleeve insulated from the housing by a shock-damping bush threadingly engaged with an internal wall of the housing; and means for reversing the direction impact is imposed on the housing for facilitating removal of the housing from a formed hole or when it becomes lodged in a rock, for example.



1. A pneumatically-operated impact-action self-propelled mechanism for driving holes in the earth by compacting the soil about the hole being made, comprising, in combination, a housing with a front end portion; means for supplying air; a sleeve mounted in the rear end portion of said housing for communicating with said means for supplying compressed air; an impact member for reciprocating inside said housing and delivering impacts in the direction of the front end portion of said housing in the course of a hole making, said impact member forming together with said housing a front chamber of a variable volume and together with said sleeve a rear chamber of a variable volume; said sleeve sealingly entering said impact member for relative sliding movement and functioning to pass compressed air into said chambers to effect reciprocation of said impact member; passages in said impact member for alternately communicating said front chamber with said rear chamber and atmosphere when the position of the impact member changes relative to said sleeve; and a resilient shock-damping means inside the rear end portion of said housing and having longitudinal passages for air pass from said front chamber into the atmosphere, said sleeve being mounted inside said shock-damping means.
 2. A pneumatically-operated mechanism according to claim 1, in which said shock-damping means includes a nut fixed outside thereof and screwed into the rear end portion of said housing.
 3. A pneumatically-operated mechanism according to claim 1, in which said resilient shock-damping means comprises a cylinder circumposed about said sleeve.
 4. A pneumatically-operated mechanism according to claim 1, including means on said sleeve for changing the mode of operation of said impact member so that the housing is driven rearwardly.
 5. A pneumatically-operated mechanism according to claim 4; said sleeve being selectively rotatable in said impact member and screwed into said shock-damping means in such a manner to be displaced along the axis of said housing in such a manner that the position of the sleeve relative to said housing can be altered to change the direction of impacts delivered by said impact member for causing reversal of the mechanism operation; said impact member delivering impacts in the direction of the front end portion of said housing when said sleeve occupies a corresponding front position and delivering impacts in the direction of the rear end portion of said housing when said sleeve occupies a corresponding rear position.
 6. A pneumatically-operated mechanism according to claim 5, in which said shock-damping means and sleeve include external projections which coacting to limit the selective rotation of said sleeve with respect to said shock-damping means.
 7. A pneumatically-operated mechanism according to claim 5, in which said shock-damping means includes a casing connected therewith and including threads cooperating with a threaded connection on said sleeve.
 8. A pneumatically-operated mechanism according to claim 5, in which said shock-damping means includes a nut secured outside thereof and screwed into a rear end portion of said housing for receiving impacts delivered by said impact member when the mechanism is driven out of a hole. 